Date:         Sat, 6 Mar 2010 11:11:45 -0500
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: AIR FLOW METER
Comments: To: Tom Hargrave <thargrav@hiwaay.net>
In-Reply-To:  <003501cabd43$53998930$facc9b90$@net>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 10:40 AM 3/6/2010, Tom Hargrave wrote:
>The fact that the carbon resistor is laser trimmed is what I was eluding to
>when I stated that relocating the wiper isn't a 100% fix. The problem is
>that the missing carbon track across the carbon resistor changes the value
>all the way across the sweep even when you relocate the wiper.

Dear Tom,

I'd like to see that tested.  There has to be some reason that they
made the thing so elaborate, and I strongly suspect that it's to
reduce the sensitivity of the device to the precise tracking radius
of the wiper.  Remember that it's acting as a potentiometer and its
output is a smoothly varying voltage; but if you measure
wiper-to-ground resistance while moving the vane it varies all over
the place.  I wish I had one to do some measurements on.  My
impression is that the large carbon surface contributes comparatively
little to the resistance.

Yours,
David